Virtually all domestic electric water heaters incorporate thermostats and such components conventionally are located immediately adjacent to the heater tank and within the interior of the heater housing.
While electric water heater thermostats are adjustable, typically by means of a rotatable setscrew, the adjustment operation is an awkward and time-consuming process because access to the setscrew is difficult and inconvenient. For one thing, a person wishing to adjust the thermostat must first remove at least one cover plate or door affixed to the outer casing or housing to obtain access to the interior of the housing. Tools usually must be employed to accomplish this step and they are not always readily available. Then too, after the cover plate is removed, it is usually necessary for an individual to dig through the insulation between the housing and the tank to locate the adjustable setscrew of the thermostat. Not only can the insulation cause irritation to the skin, great care must be taken to avoid contact with live wiring or terminals employed in the water heater. Inadvertent contact can cause physical injury and even death.
Reversing the process just described is just as inconvenient. Cover plates might not be replaced, severely degrading the insulation properties of the heater, wasting energy, and creating an electrical hazard.
Most electric heater thermostats are factory set at a predetermined temperature, most commonly in the order of 140 degrees Fahrenheit. Because of the afore-described difficulties encountered when attempting to change the thermostat setting, most electrical water heaters simply remain at this preset temperature, resulting in the consumption in toto of countless megawatt hours of electricity. Heat from the electric water heaters simply dissipates to the atmosphere, even when the premises is not occupied. Also, of course, one may find that the preset temperature results in water hotter than desired and the complexities of adjusting the thermostat deter a downward temperature adjustment, again resulting in a waste of energy.